WO2012159295A1

WO2012159295A1 - Entropy decoding method and device

Info

Publication number: WO2012159295A1
Application number: PCT/CN2011/076357
Authority: WO
Inventors: 徐苏珊
Original assignee: 深圳市融创天下科技股份有限公司
Priority date: 2011-05-25
Filing date: 2011-06-25
Publication date: 2012-11-29
Also published as: CN102355578A; CN102355578B

Abstract

An entropy decoding method and device is disclosed. The method includes: acquiring a binary bit stream; acquiring a first variable; determining the type of the current code word based on the range of the first variable; and performing decoding with the corresponding decoding method based on the type of the current code word. The device includes: an acquiring unit, a code word type determining unit and a decoding unit. The solution designs the rule of code words and the order of code tables by analyzing the probability distribution of syntax elements, calculates the sequential index of the code words in the code tables based on the rule of code words, and indexes and sorts the syntax elements in the code tables so that the fast decoding is implemented.

Description

Technical field

The present invention relates to the field of video coding and decoding, and in particular, to an entropy decoding method and apparatus.

Background technique

As one of the most important links in multimedia communication, video coding technology effectively solves the problem of encoding and compressing massive digital video data. It is the premise of digital information transmission, storage and playback. At present, the mainstream international standards for video compression mainly include MPEG-x and H.26x. These video coding algorithms are block-based hybrid coding methods, which eliminate video time redundancy by motion estimation and motion compensation, and discretize the difference image. The cosine transform transform eliminates spatial redundancy and performs variable length coding on the quantized coefficients to eliminate statistical redundancy.

In 2003, ISO/IEC (Moving Picture Experts Group) Motion Picture Experts Group and ITU-T (ITU-T for ITU Telecommunication Standardization Sector) The Video Coding Experts Group (VCEG) has teamed up to develop the latest video coding standard H.264/AVC (the latest standard jointly introduced by the advantages of H.263+ and MPEG-4), with the main purpose of achieving higher coding efficiency. And better network affinity. Compared to the H.263+ and MPEG-4 ASP standards, 50% of the code stream is saved under the same reconstructed image quality. The high compression performance of H.264 comes at the cost of high codec complexity. A number of new coding algorithms have been adopted: intra prediction, multiple reference frame motion compensation, enhanced entropy coding, deblocking filtering, and so on. This leads to a significant increase in the complexity of video codecs, and the huge amount of computation can cause severe power consumption, which challenges the implementation of video entropy decoding for embedded platforms.

In the H.264/AVC standard, residual data is integer-transformed and quantized, and then sent to an entropy encoder for encoding. H.264 uses two broad categories of entropy coding methods: arithmetic coding and variable length coding. Variable length coding is further divided into exponential Columbus coded Exp-Golomb and context-based adaptive variable length coding CAVLC. Index Columbus coding uses a fixed coding rule to encode various syntax elements, such as image sequence parameters, image layer parameters, slice parameters, macroblock types, coding block types, etc.; and prediction residual coefficients are encoded according to entropy coding mode. To choose context-based Adaptive Variable Length Coding (Cycle-based Adaptive Variable Length Coding) or Context-based Adaptive Binary Arithmetic Coding (CAB AC) H.264 The CAVLC entropy coding of the /AVC video coding standard makes full use of the context information, and achieves a good coding effect by establishing multiple code table adaptive selection optimization. The CABAC entropy coding of H.264/AVC belongs to arithmetic coder. The performance of arithmetic coding is better than that of variable length coding, and CABAC is closer to Shannon's theorem through adaptive probability estimation and update and binary arithmetic coding. However, the computational complexity of the algorithm is high, and the hardware implementation requirements are complex. It is an improvement of the coding efficiency by the complexity of software and hardware.

For applications such as real-time video communication such as mobile video, the entropy codec technology generally uses CAVLC codec and index Columbus codec. CAVLC still adopts the Huffman coding idea to construct a binary tree with the smallest length of the weighted path according to the probability of occurrence of characters, so that the average codeword length is the shortest, and the prefixes of each symbol code are different, that is, the coding of any symbol. Neither will be a prefix for another symbolic code. Based on the traditional variable length coding method, CAVLC defines multiple sets of code tables by introducing an adaptive model of context, and dynamically switches the code table according to the characteristics of coded code words. Therefore, CAVLC is in the currently published video standard. The most efficient coding adaptive variable length coding technique.

The main steps of the traditional entropy decoding operation are as follows: Read the received binary code stream and then traverse the lookup table matching codeword bit by bit. This requires repeatedly querying the variable length code table to determine the exact matching codeword, thereby determining the codeword. Decoding according to the corresponding relationship between the codeword and the corresponding syntax element, and obtaining the value of the corresponding syntax element. However, this also causes the CAVLC decoding process to be too computationally intensive. On the one hand, CAVLC decoding must distinguish codewords of different lengths from successive bitstreams. For example, the full search algorithm needs to traverse the entire binary tree, which requires multiple readings and judgments. Therefore, the table lookup process takes a lot of time; Since the codeword tree is sparse, the storage space of the code table increases with the length of the codeword. The index has grown, but most of it is vacant and has not been used effectively.

Specifically, the lookup table operation here mainly involves two technical problems: 1) How to determine the complete codeword of variable length; 2) Indirectly obtain the corresponding syntax element from the codeword by looking up the table. Obviously, to solve these two technical problems, it is first necessary to store a complex variable length code table in the memory. Secondly, bit by bit traversing the lookup table to match the code words, and repeatedly reading and writing memory operations will also lead to a sharp increase in power consumption.

In summary, the high efficiency of CAVLC coding is at the expense of numerous code tables. Too many code tables mean that the codec operation requires more computing resources. The operation of entropy decoding can generally be implemented by a Look Up Table (LUT) structure. The lookup table mode can obtain better speed by occupying memory space, but these methods are suitable for embedded terminals such as mobile phones and PDAs. Resources are often very limited, and the lookup table traverses the lookup table to match the codewords in the decoding process. Repeated read and write memory operations also lead to a sharp increase in power consumption. Therefore, it is necessary to propose an entropy suitable for low resource requirements of embedded platforms. Decoding implementation method.

Summary of the invention

An object of the embodiments of the present invention is to provide an entropy decoding method and apparatus.

The entropy decoding method is specifically:

Obtaining a prefix portion of the codeword according to the binary bit stream;

Obtaining a first variable according to the binary bit stream; if the first variable is within a variable length codeword parameter, determining that the decoding mode is one of the first to fourth decoding modes; if within the fixed length codeword parameter range, determining The current codeword is a fixed length codeword;

Determining, according to the prefix, whether the current codeword is a special short code according to the prefix, and if so, decoding according to a preset special short code decoding formula to obtain the first parameter And the second parameter; if otherwise, according to the prefix portion of the codeword, the preset corresponding decoding formula is selected for decoding, and an index value is obtained, and the first parameter and the second parameter are obtained according to the index value;

When it is determined that the current codeword is a fixed length codeword, the index value is set to be equal to the fixed length codeword; and the first parameter and the second parameter are obtained according to the index value. Corresponding to the method, an embodiment of the present invention further provides an entropy decoding apparatus, where the apparatus includes: an acquiring unit, a decoding mode determining unit, a variable length code decoding unit, and a fixed length code decoding unit; and an acquiring unit, configured to acquire a binary a bitstream, obtaining a prefix portion of the codeword according to the binary bitstream; acquiring the first variable according to the binary bitstream;

a decoding mode determining unit, configured to determine after acquiring the first variable; if the first variable is within the variable length codeword parameter range, determining that the decoding mode is one of the first to fourth decoding modes; Within the range of the word parameters, determining that the current codeword is a fixed length codeword; a variable length code decoding unit, configured to determine, according to the prefix, whether the current codeword is based on the prefix in one of the determined first to fourth decoding modes It is a special short code; if it is decoded according to a preset special short code decoding formula, the first parameter and the second parameter are obtained; if otherwise, the corresponding decoding formula is selected according to the prefix part of the code word for decoding, and an index is obtained. a value, the first parameter and the second parameter are obtained according to the index value; the fixed length code decoding unit is configured to: when determining that the current codeword is a fixed length codeword, set an index value equal to the fixed length codeword; obtain according to the index value The first parameter and the second parameter.

An object of the embodiments of the present invention is to provide an entropy decoding method and apparatus. By analyzing the probability distribution of the syntax elements, the codeword rules and the order of the code table are newly designed. The order index of the codewords in the code table is calculated according to the codeword rules, and the syntax elements in the code table are indexed and sorted. Fast decoding operation. In addition, a special short codeword with a high frequency of use is directly calculated into a simple arithmetic expression to calculate the corresponding syntax element value. The embodiment of the present invention eliminates the operation of traversing the binary tree and the operation of matching the codeword, thereby greatly reducing the requirement of the entropy coding algorithm for hardware such as memory.

DRAWINGS

1 is a flow chart of a preferred embodiment of the entropy decoding method of the present invention;

2 is a diagram showing a relationship between a current macroblock and a left and upper macroblock of a preferred embodiment of the entropy decoding method of the present invention; 3 is a schematic structural diagram of a preferred embodiment of an entropy decoding apparatus of the present invention;

4 is a decoding mode determining unit in a preferred embodiment of the entropy decoding apparatus of the present invention. FIG. 5 is a special short code decoding unit in a preferred embodiment of the entropy decoding apparatus of the present invention. FIG. 6 is an entropy decoding apparatus of the present invention. Non-special short code decoding unit in a preferred embodiment

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. For the convenience of description, only the parts related to the embodiments of the present invention are shown. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In video coding, a macroblock is the basic unit of video coding. The macroblock size is 16x16. Each macroblock consists of four 4x4 blocks, each block consisting of one 4x4 luma block and two chroma blocks. For image blocks, the predicted and quantized residual coefficients require the corresponding syntax elements of the image block residual coefficients to be obtained by scanning. The syntax elements that need to be encoded are: Level (the magnitude of non-zero coefficients), Run (a continuous zero-coefficient run before a non-zero coefficient), and data terminators. Usually, the entropy coding performs pre-processing on the Zigzag scan of the system after the prediction transform is quantized, and the non-zero coefficient encountered in the scan is recorded as Level, and the continuous zero-coefficient run before the non-zero coefficient is recorded as Run. Of course, the entropy coding of video coding is encoded in addition to the syntax elements of the residual coefficients, and other syntax elements of the auxiliary information need to be encoded, such as motion vectors, image sequence parameters, picture layer parameters, slice parameters, macroblock types. , coding block type, etc.

Based on the traditional variable length coding method, CAVLC of H.264/AVC video coding standard defines multiple sets of code tables based on the adaptive model of context, and dynamically according to the characteristics of coded code words. The code table is switched, and the Level and Run are separately coded, and the best coding efficiency effect in the currently released video standard is obtained. The basic principle of CAVLC coding still follows the Huffman coding principle, that is, the symbol with high probability is assigned a short codeword, and the symbol with a small probability is assigned a long codeword, so as to achieve the shortest average code length.

Therefore, the embodiment of the present invention will follow the basic idea of the CAVLC coding method of the H.264/AVC video coding standard and the statistical probability distribution of the corresponding syntax elements, but the code table is completely new. Therefore, the residual coefficient syntax elements that need to be processed mainly include: (a) coeff_token (the number of non-zero coefficients TotalCoeff and the number of trailing coefficients TrailingOnes); (b) the sign of the trailing coefficient trailing- ones-sign- Flag; (c) non-zero coefficient § value (Level); (d) total-zeros; (e) run- before.

The decoding operation of these parameter coefficient syntax elements mainly requires two technical conditions: the requirement of memory resources and the power consumption of the bit-by-bit traversal lookup table, which poses a challenge to the video decoding design of the embedded terminal. In the embodiment of the present invention, the codewords are sorted by introducing a code table sequential index by analyzing the probability distribution of the codeword rules and the syntax elements, and the special short expressions of the high-frequency special short codewords are directly calculated into corresponding corresponding expressions. The value of the syntax element eliminates the operation of traversing the binary tree and the operation of matching the codeword, thereby greatly reducing the requirement of the entropy coding algorithm for hardware such as memory, and is very suitable for the method and system for entropy decoding application of the embedded terminal.

In order to obtain high entropy coding, each syntax element of the residual coefficient is designed with multiple code tables, which are adaptively selected through context. The Huffman coding principle, that is, a symbol with a high probability of assigning a short codeword and a symbol with a small probability of a long codeword, thereby achieving the shortest average code length. The codeword in the code table constructs the binary tree with the smallest length of the weighted path according to the probability of occurrence of the syntax element, so that the average codeword length is the shortest, and the prefixes of each symbol code are different, that is, the coding of any syntax symbol is It does not become a prefix for another syntax symbol encoding. Embodiment 1 According to the above idea, an embodiment of the present invention provides an entropy decoding method, where the method may be: acquiring a first variable according to a binary bit stream;

Determining the type of the current codeword according to the range of the first variable; According to the type of the current codeword, the corresponding decoding method is used for decoding.

If the type of the current codeword is a variable length codeword, the method further includes the step of: obtaining a prefix portion of the codeword in the binary bitstream before the "decoding according to the type of the current codeword using the corresponding decoding method";

"Decoding according to the type of the current codeword by using a corresponding decoding method" may be: when determining that the current codeword is a variable length codeword, determining that the decoding mode is a variable length codeword decoding mode; according to the prefix portion of the codeword Determining whether the current codeword is a special short code, if yes, decoding according to a preset special short code decoding formula to obtain a first parameter and a second parameter; if otherwise, selecting according to the prefix in the variable length codeword decoding mode The preset decoding formula is decoded to obtain an index value, and the first parameter and the second parameter are obtained according to the index value.

If the type of the current codeword is a fixed length codeword, "decoding according to the type of the current codeword using the corresponding decoding method" may be: determining that the decoding mode is a fixed length codeword decoding mode; setting the index value value equal to the fixed length codeword The value is used to find a preset fixed length code table according to the index value, and obtain a first parameter and a second parameter corresponding to the index value.

See Figure 1, the method is specifically:

In the embodiment of the present invention, setting the first parameter to the number of trailing coefficients TrailingOnes, setting the second parameter to the number of non-zero coefficients TotalCoeff;

Step 101: Obtain a first variable (NC); if the first variable (NC) is within a variable length codeword parameter range, for example, may be -1≤NC<8; then determine that the decoding mode is the first to fourth decoding modes. If the first variable (NC) is within the range of the fixed length codeword parameter, for example, NC ≥ 8, then the current codeword is determined to be a fixed length codeword, and step 106 is performed; The first variable obtained in this step (the method of Ncy can be:

(1) Pre-calculating the first non-zero coefficient number (NA) of the 4X4 macroblock to the left of the current macroblock and the second non-zero coefficient number (NB) of the 4X4 macroblock above the current macroblock; the current macroblock and the left and upper macroblocks Position map, see Figure 2.

When both NA and NB are valid, NC=(NA+NB)/2; when NB is valid, NA is invalid, NC=NB; when NB is invalid, NA is valid, NC=NA; Table 1 NC and NA and NB Corresponding relationship

(2) "If -1 ≤ NC < 8 in the step; then determining that the decoding mode is one of the first to fourth decoding modes" may be:

For example: If 0≤NC<2, select the first decoding mode (Table 2, the first variable length code table VLC-1) for decoding;

If 2 ≤ NC < 4, the second decoding mode (Table 3, second variable length code table VLC-2) is selected for decoding;

If 5≤NC<8, the third decoding mode (Table 4, third variable length code table VLC-3) is selected for decoding; If NC = -1, the fourth decoding mode is selected (Table 5, fourth variable length code table VLC-4);

(3) in the step, when NC≥8, determining that the current codeword is a fixed-length codeword for decoding; Step 102: Acquiring a binary bitstream, and obtaining a prefix portion of the codeword according to the binary bitstream;

For example, the prefix portion may be obtained by using a first "1" detector; Step 103: In the first to fourth decoding modes determined in step 101, determining whether the current codeword is a special short code according to the prefix; if yes, performing the step 104; If otherwise, step 105 is performed; the step may be: assigning the number of "0"s of the prefix part to the intermediate variable PrefixNum, and then determining whether the codeword is special according to the relationship between the intermediate variable PrefixNum and the threshold. Short code. The threshold S can be determined according to the first variable NC, for example:

When 0≤NC<2, it is the first decoding mode, then the threshold S can be set to 3, and when PrefixNum<3, it is determined that the current codeword is a special short code;

When 2≤NC<4, it is the second decoding mode, then the threshold S can be set to 2, and when PrefixNum<2, it is determined that the current codeword is a special short code;

When 5≤NC<8, it is the third decoding mode, then the threshold S can be set to 1, and when PrefixNum<1, it is determined that the current codeword is a special short code;

When NC=-1 is the fourth decoding mode, then the threshold S can be set to 3, and when the PrefixNum<3, the current codeword is determined to be a special short code; Step 104: The first to the determined in step 101 In one of the fourth decoding modes, decoding is performed according to a preset special short code decoding formula, and the first parameter TrailingOnes and the second parameter are obtained. TotalCoeff;

For example: (1) When it is determined that 0≤NC<2, it is the first decoding mode:

TrailingOnes=TotalCoeff=PrefixNum

(2) When it is determined that 2≤NC<4, it is the second decoding mode:

When the special short code is in the second decoding mode, the binary bit stream is read according to the preset S _U ffixl _en gth=l, and Suffix is obtained;

TrailingOnes=TotalCoeff=(Prefix«l)+Suffix;

(3) When it is determined that 5≤NC<8, it is the third decoding mode:

When the special short code is in the third decoding mode, the binary bit stream is read according to the preset S _U ffixl _en gth=3, and Suffix is obtained;

TotalCoeff= Suffix

TrailingOnes=3 (Suffix/4)+(Suffix%4) (l-Suffix/4)

Or TrailingOnes= 3xSuffix[2:2]+suffix[l :0] x(~ Suffix[2:2])

Among them, the two formulas for obtaining TrailingOnes are actually the same, the former one is simple calculation, and the latter one is based on bit operation;

(4) When determining NC=-1, it is the fourth decoding mode.

TrailingOnes = TotalCoeff = 2 PrefixNum[l : l] + ( ~ PrefixNum[0:0]) (- PrefixNum[l : l])

Where TrailingOnes is the first parameter, TotalCoeff is the second parameter, PrefixNum is the intermediate variable, Prefix is the prefix, Suffix is the suffix, Suffix[2:0] represents the 2nd to 0th bit of the 3-bit binary number, Suffix[l: 0] represents a 2-bit binary number from the 1st to the 0th bit, and Suffix[2:2] represents a 1-bit binary number of the 2nd bit. PrefixNum [1 : 0] represents the 2-bit binary number from bit 1 to bit 0, PrefixNum[l : l] represents the 1-bit binary number of the first, and PrefixNum [0:0] represents The 1-bit binary number of the 0th bit. "/" means the division operator, "%" means the remainder operator, and "~" means the bit is the inverse operator. Step 105: Decoding according to the prefix selection corresponding preset decoding formula in the first to fourth decoding modes determined in step 101, obtaining an index value, and the index value characterizing the syntax element (the first parameter TrailingOnes and The second parameter TotalCoeff) is arranged in order to obtain the first parameter TrailingOnes and the second parameter TotalCoeff according to the index value.

The step of decoding is performed according to determining different decoding modes and selecting a corresponding preset decoding formula by using the prefix, and obtaining an index value may be:

(1) When determining the first decoding mode,

Suffixlength=(PrefixNum>=9 && PrefixNum<13) ? 3 : 2 Read the binary bit stream according to the Suffixlength to obtain Suffix;

((PrefixNum-3)«2) + Suffix 3 < Pr efixNum < 9

Index =

((PrefixNum-9)«3)+Suffix+24 9 < Pr efixNum<l 3

56 + Suffix 13 ≤ Pr efixNum where Index is the index value, PrefixNum is the intermediate variable, Suffix is the suffix, Suffixlength is the suffix length, "&&" means the logical AND operator, "? : " means the conditional operator, and "«" means Bit shift operation

(2) When determined to be the second decoding mode,

Suffixlength=(PrefixNum>=7) ? 3 : 2 Read the binary bit stream according to the Suffixlength to obtain Suffix;

Index = ((PrefixNum-2)«2)+Suffix 2 < Pr efixNum<7

((PrefixNum-7)«3)+Suffix+20 7 < Pr efixNum where Index is the index value, PrefixNum is the intermediate variable, Suffix is the suffix, Suffixlength For the suffix length, "? : " means that the conditional operator "<<" means a bitwise left shift operation.

(3) when determined to be the third decoding mode, read the binary bit stream according to the preset S _U ffi _X length = 3, to obtain Suffix;

Index= ((PrefixNum-3)«2) + Suffix;

Where Index is the index value, PrefixNum is the intermediate variable, Suffix is the suffix, and "" means the bitwise left shift operation.

(4) when determined to be the fourth decoding mode, read the binary bit stream according to the preset S _U ffi _X length = 2, to obtain Suffix;

Index=(PrefixNum-3)«3) + Suffix

And in step 105, the obtaining the index value, obtaining the first parameter and the second parameter according to the index value may be: after obtaining the index value, in determining one of the first to fourth decoding modes, according to The index value searches for a preset parameter table, and obtains a first parameter and a second parameter corresponding to the index value. In the first decoding mode, the corresponding parameter table of the search preset is Table 2, the first variable length code table (VLC-1); in the second decoding mode, the parameter table of the corresponding search preset is Table 3. The second variable length code table (VLC-2); wherein in the third decoding mode, the corresponding parameter table of the search preset is Table 4, the third variable length code table (VLC-3); in the fourth decoding mode The corresponding parameter table for finding the preset is Table 5, the fourth variable length code table (VLC-4). Step 106: The current codeword determined in step 101 is a fixed length codeword; if the fixed length codeword length is a preset length, the index value Index is set to be equal to the fixed length codeword; and the first parameter is obtained according to the index value. And the second parameter. The preset length of the fixed length codeword is an integer not less than log ₂ N, and N is the number of values of the syntax element; in this example, the preset length may be 6.

The step may be: when determining that the current codeword is a fixed length codeword, after setting the index value equal to the fixed length codeword, searching for the preset fixed length code table according to the index value, and obtaining the first parameter corresponding to the index value and The second parameter. The following describes from the perspective of a specific codeword:

(1) Non-special short code case of the first decoding mode:

According to the method of step 101, according to the macroblock situation, the current NC=1 is obtained, then according to the determination in step 101, if "0≤NC<2, the first decoding mode (VLC-1 code table) is selected for decoding. ", can determine that the current decoding mode is the first decoding mode;

Obtain a binary bit stream OOOO Ol lOxxxxx according to the method of step 102, then the prefix part is 0000 01;

According to the method of step 103, since the prefix part is 0000 01, the intermediate variable PrefixNum=5 is obtained; since it is in the first decoding mode, the threshold S=3, then PrefixNum=5>3, so the codeword is not a special short code. ;

According to the method of step 105, since it is determined to be the first decoding mode;

Then according to the preset formula: Suffixlength=(PrefixNum>=9 && PrefixNum<13)? 3: 2 =(5>=9 && 5<13)? 3: 2=2

PrefixNum is the intermediate variable, Suffix is the suffix, Suffixlength is the suffix length, "&&" means "and", "(judgment condition) ? a: b" means: when the judgment condition is established, then a, when the judgment condition is not true Take b.

Obtain Suffix according to the Suffixlength=2 read binary bit stream 0000 01 ΙΟχχχχχ Is "10";

((PrefixNum-3)«2) + Suffix 3 < Pr efixNum < 9

Index =

((PrefixNum-9)«3)+Suffix+24 9 < Pr efixNum<l 3

56 + Suffix 13 ≤ Pr efixNum Since PrefixNum=5, then calculate according to the formula ((PrefixNum-3)«2) + Suffix, get the index value Index, then finally get Index=(PrefixNumb-3)«2+Suffix)= ((5-3)«2)+2=10.

Then according to Index=10, to the first variable length code table (VLC-1) lookup table to obtain the first parameter TrailingOnes and the second parameter TotalCoeff; then through the table 1 - the first variable length code table VLC-1 and the index value 10 can Find TrailingOnes as 0 and TotalCoeff as 3.

Table 2 The first variable length code table VLC-1

(2) The special short code case of the first decoding mode:

According to the method of step 102, a binary bit stream OOlOllOxxxxx is obtained, and the prefix part is 0010110;

According to the method of step 103, since the prefix part is 0000 01, the intermediate variable is obtained. PrefixNum=2; Since it is in the first decoding mode, the threshold S=3, then PrefixNum=2<3, so the codeword is a special short code;

According to the method in step 104, TrailingOnes=TotalCoeff=2 can be known according to TrailingOnes=TotalCoeff=PrefixNum _;

(3) a non-special short code condition of the second decoding mode;

According to the method of step 102, a binary bit stream OOOO Ol lOlxxxx is obtained, then the prefix part is 0000 01; according to the method of step 101, according to the macro block situation, the current NC=3 is obtained, then according to the decoding mode determined in step 10x" If 2≤NC<4, selecting the second decoding mode (the second variable length code table VLC-2 code table) for decoding", it may be determined that the current decoding mode is the second decoding mode;

According to the method of step 103, since the prefix part is 0000 01, the intermediate variable PrefixNum=5 is obtained; since it is in the second decoding mode, the threshold S=2, then PrefixNum=5>2, so the codeword is not a special short code. ;

According to the method of step 105, since it is determined to be the second decoding mode;

Then according to the preset formula: Suffixlength=(PrefixNum>=7) ? 3 : 2 =(5>=7 )? 3 : 2

PrefixNum is the intermediate variable, Suffix is the suffix, Suffixlength is the suffix length, and "? : " is the conditional operator.

Reading the binary bit stream 0000 01 根据 according to the Suffixlength=3, and obtaining Suffix as "101";

Index = <! ((PrefixNum-2)«2)+Suffix 2 < Pr efixNum<7

((PrefixNum-7)«3)+Suffix+20 7 < Pr efixNum Since PrefixNum=5, then according to the formula ((PrefixNum-3)«2) + Suffix calculation, get the index value Index, then finally get Index=(PrefixNumb-2)«2+Suffix)=((5-2)« 2) +5 = 17

Then according to Index=17, to the second variable length code table (VLC-2) lookup table to obtain the first parameter TrailingOnes and the second parameter TotalCoeff; then through Table 2 - the second variable length code table VLC-2 and the index value 14 can Find TrailingOnes as 2. TotalCoeff is 6.

Table 3 Second variable length code table VLC-2

(4) Special short code case for the second decoding mode:

According to the method of step 101, according to the macroblock situation, the current NC=3 is obtained, then according to the determination in step 101, if "2≤NC<4, the second decoding mode (VLC-2 code table) is selected for decoding. ", can determine that the current decoding mode is the second decoding mode;

According to the method of step 102, a binary bit stream 011011 lxxx is obtained, and the prefix part is 01;

According to the method of step 103, since the prefix part is 01, the intermediate variable PrefixNum=l is obtained _; since it is in the second decoding mode, the threshold S=2, then PrefixNum=l<2, so the codeword is a special short code;

According to the method in step 104, according to: reading the binary ratio according to the preset S _U ffi _X length=l TrailingOnes=TotalCoeff=(Prefix«l)+Suffix= (1«1) +1=2+1=3;

(5) Non-special short code case of the third decoding mode:

According to the method of step 101, according to the macroblock situation, the current NC=6 is obtained, then according to the determination in step 101, if "5≤NC<8, the third decoding mode (VLC-1 code table) is selected for decoding. ", can determine that the current decoding mode is the third decoding mode;

According to the method of step 102, a binary bit stream 0000 OllOlxxxx is obtained, and the prefix part is 000001;

According to the method of step 103, since the prefix part is 0000 01, the intermediate variable PrefixNum=5 is obtained; since it is in the third decoding mode, the threshold S=l, then PrefixNum=5>l, so the codeword is not a special short code. ;

According to the method of step 105, since it is determined to be the third decoding mode;

Then according to the preset formula:

Index=((PrefixNum-3)«2) Ten Suffix where Index is the index value, PrefixNum is the intermediate variable, Suffix is the suffix, and "" means the bitwise left shift operation.

Wherein, in the third decoding mode, since the codeword suffix length is preset to 3, the suffix "101" can be obtained according to the binary bit stream 0000 OllOlxxxx; therefore Index=((5-3) «2) +5 = 8 +5=13;

Then find the third variable length code table (VCL-3) by Index=13 to get TrailingOnes = 1, TotalCoeff=7

Table 4 Variable Length Code Table 3 (VLC-3)

(6) Special short code case for the third decoding mode:

According to the method of step 101, according to the macroblock situation, the current NC=6 is obtained, then according to the determination in step 101, if "5≤NC<8, then the third decoding mode is selected for decoding", the current decoding mode can be determined. Is the third decoding mode;

According to the method of step 102, a binary bit 10011 lxxx is obtained, then the prefix part is

10;

According to the method of step 103, since the prefix portion is 1, the intermediate variable PrefixNum=0 is obtained; since it is in the third decoding mode, the threshold S=l, the codeword is a special short code;

According to the method in step 104, the binary bit stream is read according to the preset Suffixlength=3, and Suffix=001 is obtained;

TotalCoeff= Suffix

TrailingOnes=3 (Suffix/4)+(Suffix%4) (l-Suffix/4)

Or TrailingOnes= 3xSuffix[2:2]+suffix[l :0] x(~ Suffix[2:2])

In the third decoding mode, since the codeword suffix length is preset to 3, the suffix "001" can be obtained according to the binary bit stream 10011 lxxx;

Where TrailingOnes is the first parameter, TotalCoeff is the second parameter, Prefix is the prefix,

Suffix suffix; Suffix[2:0] represents the 3-bit binary number from bit 3 to bit 0, Suffix[l:0] A 3-bit binary number indicating the 2nd to the 0th bit, and Suffix[2:2] indicating the 1-bit binary number of the 2nd bit. "/" means the division operator, "%" means the remainder operator, "~" means the bit is the inverse operator; then by: TrailingOnes=3xSuffix[3:3]+suffix[2:0] x(~ Suffix[ 3:3])=3x0+lx(~ 0)=0+1 1 = 1.

(7) Non-special short code case of the fourth decoding mode:

According to the method of step 101, according to the macroblock situation, the current NC=-1 is obtained, then according to the determination in step 101, "NC=-1, then select the fourth decoding mode (VLC-4 code table) for decoding" , determining that the current decoding mode is the fourth decoding mode;

According to the method of step 102, a binary bit stream OOOO OlOOlxxxx is obtained, and the prefix part is 0000 01;

According to the method of step 103, since the prefix part is 0000 01, the intermediate variable PrefixNum=5 is obtained; since it is in the fourth decoding mode, the threshold S=3, then PrefixNum=5>3, so the codeword is not a special short code. ;

According to the method of step 105, since it is determined to be the fourth decoding mode;

Then according to the preset formula:

Index=((PrexfixNum-3)«2) Ten Suffix where Index is the index value, PrefixNum is the intermediate variable, and Suffix is the suffix. "" indicates a bitwise left shift operation.

Wherein, in the third decoding mode, since the codeword suffix length is preset to 3, the suffix is "001" according to the binary bit stream OOOOOOOOxxxx; therefore Index=((5-3) «2) +1 = 9 ; Then, by Index=9; find the fourth variable length code table (VCL-4), you can get TrailingOnes=2, TotalCoeff=4o, Table 5, Variable Length Code Table 4 (VLC-4)

(8) Special short code case of the fourth decoding mode: According to the method of step 101, according to the macroblock situation, the current NC=-1 is obtained, then according to the determination in step 101, "NC=-1, then select the first The fourth decoding mode is decoded. "The current decoding mode can be determined to be the fourth decoding mode. According to the method of step 102, a binary bit 10011 lxxx is obtained, and the prefix portion is

10; According to the method of step 103, since the prefix portion is 1, the intermediate variable PrefixNum = 0 is obtained; since it is in the fourth decoding mode, the threshold S = 3, the code word is a special short code. Then according to the formula

TrailingOnes=TotalCoefF= 2xPrefixNum[l:l]+(~ PrefixNum[0:0])x(~ PrefixNum[l:l]) = 2x0+0x1=0

Where TrailingOnes is the first parameter, TotalCoeff is the second parameter, PrefixNum is the intermediate variable, PrefixNum [1:0] represents the 1-bit binary number from the 1st to the 0th, Suffix[l:l] Indicates the 1-bit binary number of the first, and Suffix[0:0] represents the 1-bit binary number of the 0th bit. "~" indicates that the bit is inverted.

(9) Fixed length codewords

According to the method of step 101, according to the macroblock situation, the current NC=9 is obtained, then according to the determination in step 101, if the first variable (NC) is within the fixed length codeword parameter range, NC≥8, the current current is determined. The codeword is a fixed length codeword"; therefore, it can be determined that the current codeword is a fixed length codeword;

Then, according to the method of step 106, a binary bit 10011 lxxx is obtained. In this example, since the fixed length codeword length is 6, the index value Index=fixed length codeword=100111=39 is set, according to Index=39 to Table V- The long code table gets TrailingOnes=0; TotalCoeff=12.

In Tables 1 to 4 provided by the embodiments of the present invention, for the convenience of description, the index values can be quickly found in the table. TrailingOnes and TotalCoeff respectively list TrailingOnes, TotalCoeff and Index, which are actually in the system, Tables 1 to 4 Only TrailingOnes and TotalCoeff are two. Embodiment 2, corresponding to the entropy decoding method of Embodiment 1, the embodiment of the present invention further provides an entropy decoding apparatus. Referring to FIG. 3, the apparatus includes: an acquiring unit, a codeword type determining unit, and a decoding unit; The obtaining unit is configured to acquire a first variable according to a binary bit stream;

And a codeword type determining unit, configured to determine a type of the current codeword according to a range of the first variable; and a decoding unit, configured to perform decoding according to a type of the current codeword by using a corresponding decoding method.

The obtaining unit includes:

a bitstream acquisition unit, configured to acquire a binary bitstream;

The first variable acquisition unit is configured to acquire the first variable. The first variable acquiring unit is configured to: obtain the first variable specifically:

For pre-calculating the number of first non-zero coefficients of the 4X4 block to the left of the current macroblock and the current macroblock

The number of second non-zero coefficients of the 4X4 block;

When both the first non-zero coefficient number and the second non-zero coefficient number are valid, the first variable first non-zero coefficient number + second non-zero coefficient number, 11

When the number of second non-zero coefficients is valid, and the number of first non-zero coefficients is invalid, the first variable = the number of second non-zero coefficients;

When the number of second non-zero coefficients is invalid and the number of first non-zero coefficients is valid, the first variable = the number of first non-zero coefficients.

The obtaining unit further includes a prefix obtaining unit, configured to obtain a prefix portion of the current codeword according to the binary bit stream;

The codeword type determining unit is further configured to determine, according to a range of the first variable, that the type of the current codeword is a variable length codeword; the decoding unit includes: a decoding mode determining unit, a determining unit, and a special short code decoding unit; a mode determining unit, configured to: when determining that the current codeword is a variable length codeword, determine that the decoding mode is a variable length codeword decoding mode;

a determining unit, configured to determine, according to a prefix portion of the codeword, whether the current codeword is a special short code when determining that the decoding mode is a variable length codeword decoding mode;

a special short code decoding unit, configured to determine a current codeword as a special short code according to a preset The special short code decoding formula is decoded to obtain the first parameter and the second parameter.

The codeword type determining unit is configured to determine, according to the range of the first variable, that the type of the current codeword is a variable length codeword, which is specifically: when -1 ≤ the first variable <8, the type of the current codeword is determined. Variable length code word;

The structure of the decoding mode determining unit is shown in FIG. 4. The unit includes: a first decoding mode determining unit, a second decoding mode determining unit, a third decoding mode determining unit, and a fourth decoding mode determining unit;

a first decoding mode determining unit, configured to determine that if 0≤the first variable<2, determine to decode the first decoding mode;

a second decoding mode determining unit, configured to determine that if the second variable <4, the second decoding mode is determined to be decoded;

a third decoding mode determining unit, configured to determine that if the third variable <8, the third decoding mode is determined to be decoded; and the fourth decoding mode determining unit is configured to determine that if the first variable is -1, the determining is The fourth decoding mode is decoded.

Wherein the decoding mode determining unit determines that one of the first to fourth decoding modes is to be decoded,

The determining unit is configured to determine, according to the prefix, whether the current codeword is a special short code according to the prefix when determining that the decoding mode is a variable length codeword decoding mode:

And assigning the number of “0”s of the prefix part to an intermediate variable, and in the decoding mode of one of the first to fourth, if the intermediate variable is smaller than a threshold, determining that the current codeword is a special short code If the intermediate variable is greater than or equal to the threshold, determining that the current codeword is a non-special short code;

Referring to FIG. 5, the structure of the special short code decoding unit is specifically as follows:

The special short code decoding unit includes a first special short code decoding unit; The first special short code decoding unit is configured to, when determining to be the first decoding mode,

TrailingOnes=TotalCoeff=PrefixNum;

Where TrailingOnes is the first parameter, TotalCoeff is the second parameter, and PrefixNum is the middle.

The special short code decoding unit further includes a second special short code decoding unit, and the second special short code decoding unit is configured to read the binary bit stream according to the preset S _U ffi _X length=l, and obtain Suffix;

TrailingOnes=TotalCoeff=(Prefix« 1 )+Suffix;

Among them, TrailingOnes is the first parameter, TotalCoeff is the second parameter, PrefixNum is the intermediate variable, Suffix is the suffix, Prefix is the prefix, Suffixlength is the suffix length, and "" indicates the bitwise left shift operation;

The special short code decoding unit further includes a third special short code decoding unit, and the third special short code decoding unit is configured to: when determined to be the third decoding mode, read according to a preset Suffixlength=3 Take a binary bit stream, get Suffix;

TotalCoeff= Suffix; Trailing0nes=3 (Suffix/4)+(Suffix%4) (1 - Suffix/4) or TrailingOnes= 3 Suffix[2:2]+suffix[l:0] x(~ Suffix[2:2 ]); where TrailingOnes is the first parameter, TotalCoeff is the second parameter, PrefixNum is the intermediate variable, Prefix is the prefix, Suffix is the suffix, Suffix[2:0] represents the 2nd to 0th bit of the 3-bit binary number, Suffix [l:0] represents a 2-bit binary number from the 1st to the 0th bit, and Suffix[2:2] represents a 1-bit binary number of the 2nd bit. "/" means the division operator, "%" means the remainder operator, and "~" means the bit negation operator.

The special short code decoding unit further includes a fourth special short code decoding unit, and the fourth special short code decoding unit is configured to: when determined to be the fourth decoding mode, TrailingOnes = TotalCoeff = 2xPrefixNum[l: l] + ( ~ PrefixNum[0:0]) (- PrefixNum[l : l])

Where TrailingOnes is the first parameter, TotalCoeff is the second parameter, PrefixNum is the intermediate variable, PrefixNum [1:0] represents the 1-bit binary number from the 1st to the 0th, and PrefixNum[l:l] represents the 1st. Bit binary number, PrefixNum [0:0] represents the 1-bit binary number of the 0th bit, and "~" means the bit is inverted.

The decoding unit further includes: a non-special short code decoding unit, configured to: when determining, according to the prefix portion of the codeword, that the current codeword is not a special short code, according to the variable length codeword decoding mode, The prefix part of the codeword is selected to be decoded by the corresponding preset decoding formula to obtain an index value, and the first parameter and the second parameter are obtained according to the index value. The structure of the non-special short code decoding unit is as shown in FIG. 6, including: a first decoding unit; for Suffixlength=(PrefixNum>=9 && PrefixNum<13)? 3: 2 reading binary bits according to the Suffixlength Stream, get Suffix;

((PrefixNum-3)«2) + Suffix 3 < Pr efixNum < 9

Index =

((PrefixNum-9)«3)+Suffix+24 9 < Pr efixNum<l 3

56 + Suffix 13 ≤ Pr efixNum where Index is the index value, PrefixNum is the intermediate variable, Suffix is the suffix, Suffixlength is the suffix length, "&&" means the logical AND operator, "? : " means the conditional operator, and "«" means Bit left shift operation.

The non-special short code decoding unit further includes a second decoding unit; when used to determine the second decoding mode,

Index = ((PrefixNum-2)«2)+Suffix 2 < Pr efixNum<7

((PrefixNum-7)«3)+Suffix+20 7 < Pr efixNum where Index is the index value, PrefixNum is the intermediate variable, Suffix is the suffix, Suffixlength For the suffix length, "? : " indicates the conditional operator, and "<<" indicates a bitwise left shift operation. The non-special short code decoding unit further includes a third decoding unit, configured to read the binary bit stream according to the preset Suffixlength=3, and obtain Suffix;

Index=(PrefixNum-3)«2) + Suffix where Index is the index value, PrefixNum is the intermediate variable, Suffix is the suffix, and "" means the bitwise left shift operation.

The non-special short code decoding unit further includes a fourth decoding unit, configured to read the binary bit stream according to the preset S _U ffi _X length=2 when the fourth decoding mode is determined, to obtain Suffix;

Index=(PrefixNum-3)«3) + Suffix where Index is the index value, PrefixNum is the intermediate variable, and Suffix is the suffix. "" indicates a bitwise left shift operation. In the above-described entropy decoding apparatus, the "acquiring index value, obtaining the first parameter and the second parameter according to the index value" described in the non-special short code decoding unit is specifically: after obtaining the index value, in the determined variable length decoding mode And searching for the preset parameter table according to the index value, and acquiring the first parameter and the second parameter corresponding to the index value. The decoding mode determining unit further includes: a fixed length codeword decoding mode determining unit; a fixed length codeword decoding mode determining unit, configured to determine that if the first variable is ≥8, determine that the fixed length codeword decoding mode is performed. The decoding unit further includes: a fixed length codeword decoding unit, configured to determine that the decoding mode is a fixed length codeword decoding mode; set an index value value equal to a fixed length codeword value, and search for a preset according to the index value. The fixed length code table obtains the first parameter and the second parameter corresponding to the index value.

An object of the embodiments of the present invention is to provide an entropy decoding method and apparatus. By analyzing the probability distribution of the syntax elements, the codeword rules and the order of the code tables are newly designed, according to the codeword rules. The order index of the code words in the code table is calculated, and the syntax elements in the code table are indexed and sorted, thereby implementing a fast decoding operation. In addition, a special short codeword with a high frequency of use is directly calculated into a simple arithmetic expression to calculate the corresponding syntax element value. The embodiment of the invention eliminates the operation of traversing the binary tree and the operation of matching the codeword, thereby greatly reducing the requirement of the entropy coding algorithm for hardware such as memory.

A person skilled in the art can understand that all or part of the steps of implementing the above embodiments can be completed by a program to instruct related hardware, and the program can be stored in a computer readable storage medium, and the above mentioned storage medium can be It is a read-only memory, a disk or a disc.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

Rights request

An entropy decoding method, characterized in that: the method is specifically:

Obtaining the first variable according to the binary bit stream;

Determining a type of the current codeword according to a range of the first variable;

Decoding is performed according to the type of the current codeword by using a corresponding decoding method.

The entropy decoding method according to claim 1, wherein the method of “acquiring a first variable according to a binary bit stream” is specifically: pre-calculating the number of first non-zero coefficients of a 4×4 block on the left side of the current macroblock And the number of second non-zero coefficients of the 4X4 block above the current macroblock;

When the first non-zero coefficient number and the second non-zero coefficient number are both valid, the first variable the first non-zero coefficient number + the second non-zero coefficient number 2 _;

When the number of the second non-zero coefficients is valid, and the number of the first non-zero coefficients is invalid, the first variable = the number of the second non-zero coefficients;

When the number of the second non-zero coefficients is invalid and the number of the first non-zero coefficients is valid, the first variable = the number of the first non-zero coefficients.

3. The entropy decoding method according to claim 1, wherein:

The step of: "decoding according to the type of the current codeword by using a corresponding decoding method" further includes the steps of: obtaining a prefix portion of the codeword in the binary bitstream;

Decoding according to the type of the current codeword by using a corresponding decoding method, specifically: when determining that the current codeword is a variable length codeword, determining that the decoding mode is a variable length codeword decoding mode; The prefix portion of the codeword determines whether the current codeword is a special short code, and if so, decodes according to a preset special short code decoding formula to obtain a first parameter and a second parameter.

The entropy decoding method according to claim 3, wherein "determining whether the current codeword is a special short code according to a prefix portion of the codeword" is specifically:

Assigning the number of "0"s of the prefix portion to the intermediate variable,

In the variable length codeword decoding mode, if the intermediate variable is less than the threshold, determining the current codeword For special short codes, otherwise determine that the current codeword is a non-special short code.

The entropy decoding method according to claim 4, wherein the variable length codeword decoding mode comprises first to fourth decoding modes;

If 0 ≤ the first variable <2, it is determined that decoding is performed using the first decoding mode, and if the threshold is 2 ≤ the first variable <4, determining to decode using the second decoding mode, the threshold is

2;

If 5 ≤ the first variable <8, it is determined that decoding is performed using a third decoding mode, the threshold is

1;

If the first variable = -1, it is determined that decoding is performed using a fourth decoding mode, the threshold being three.

The entropy decoding method according to claim 5, characterized in that: "decoding according to a preset special short code decoding formula to obtain a first parameter and a second parameter" is specifically:

TrailingOnes=TotalCoeff=PrefixNum; when it is determined that the first decoding mode is used for decoding.

Among them, TrailingOnes is the first parameter, TotalCoeff is the second parameter, and PrefixNum is the intermediate variable.

7. The entropy decoding method according to claim 5, wherein: "decoding according to a preset special short code decoding formula to obtain a first parameter and a second parameter" is specifically:

When it is determined that the second decoding mode is used for decoding, reading the binary bit stream according to the preset S _U ffi _X length=l, obtaining Suffix;

TrailingOnes=TotalCoeff=(Prefix«l)+Suffix;

Among them, TrailingOnes is the first parameter, TotalCoeff is the second parameter, PrefixNum is the intermediate variable, Prefix is the prefix, Suffix is the suffix, Suffixlength is the suffix length, and "" indicates the bitwise left shift operation.

8. The entropy decoding method according to claim 5, wherein: "the special short code according to the preset The decoding formula is decoded to obtain the first parameter and the second parameter. Specifically, when it is determined that the third decoding mode is used for decoding, the binary bit stream is read according to the preset S _U ffi _X length=3, and Suffix is obtained.

TotalCoeff= Suffix; TrailingOnes=3 (Suffix/4)+(Suffix%4) (1 - Suffix/4) or TrailingOnes= 3 Suffix[2:2]+suffix[l:0] x(~ Suffix[2:2 ]); where TrailingOnes is the first parameter, TotalCoeff is the second parameter, PrefixNum is the intermediate variable, Prefix is the prefix, Suffix is the suffix, Suffix[2:0] represents the 2nd to 0th bit of the 3-bit binary number, Suffix [l:0] represents a 2-bit binary number from bit 1 to bit 0, Suffix[2:2] represents a 1-bit binary number of the second bit, "/" represents a division operator, and "%" represents a remainder operation The character "~" indicates that the bit is inverted.

The entropy decoding method according to claim 5, wherein "decoding according to a preset special short code decoding formula to obtain a first parameter and a second parameter" is specifically: when determining to use the fourth decoding When the mode is decoded,

TrailingOnes=TotalCoeff= 2 PrefixNum[l : l] + ( ~ PrefixNum[0:0]) (- PrefixNum[l : l]); where TrailingOnes is the first parameter, TotalCoeff is the second parameter, PrefixNum is the intermediate variable, PrefixNum [1:0] represents a 2-bit binary number from bit 1 to bit 0, PrefixNum[l: l] represents the 1-bit binary number of the first, and PrefixNum [0:0] represents the 1-bit binary number of the 0th bit. , "~" means the bit is inverted.

The entropy decoding method according to claim 5, wherein when the current codeword is not a special short code according to the prefix portion of the codeword, then according to the variable length codeword decoding mode, The prefix portion of the codeword selects a preset decoding formula for decoding, obtains an index value, and obtains a first parameter and a second parameter according to the index value.

11. The entropy decoding method according to claim 10, wherein: said "in said In the variable length codeword decoding mode, the preset decoding formula is selected according to the prefix portion of the codeword for decoding, and the index value is specifically: when decoding is performed using the first decoding mode,

((PrefixNum-3)«2) + Suffix 3 < Pr efixNum < 9

Index =

((PrefixNum-9)«3)+Suffix+24 9 < Pr efixNum<l 3

56 + Suffix 13 ≤ Pr efixNum where Index is the index value, PrefixNum is the intermediate variable, Suffix is the suffix, Suffixlength is the suffix length, "&&" means the logical AND operator, "? : " means the conditional operator, "<<" means Bitwise left shift operation.

The entropy decoding method according to claim 10, wherein: "in the variable length codeword decoding mode, a preset decoding formula is selected according to a prefix portion of the codeword for decoding, and an index value is obtained. "Specifically: when decoding is performed using the second decoding mode, Suffixlength=(PrefixNum>=7) ? 3 : 2 reading the binary bit stream according to the Suffixlength to obtain Suffix;

Index = <j ((PrefixNum-2)«2)+Suffix 2 < Pr efixNum<7

((PrefixNum-7)«3)+Suffix+20 7 < Pr efixNum where Index is the index value, PrefixNum is the intermediate variable, Suffix is the suffix, Suffixlength is the suffix length, and "? :" means the conditional operator " <<" means Bitwise left shift operation.

The entropy decoding method according to claim 10, wherein: in the variable length codeword decoding mode, a preset decoding formula is selected according to a prefix portion of the codeword for decoding, and an index value is obtained. "Specifically:

When decoding is performed using the third decoding mode, the binary is read according to the preset S _U ffi _X length=3 Bitstream, get Suffix;

The entropy decoding method according to claim 10, wherein: "in the variable length codeword decoding mode, a preset decoding formula is selected according to a prefix portion of the codeword for decoding, and an index value is obtained. "Specifically:

When decoding is performed using the fourth decoding mode, the binary bit stream is read according to the preset S _U ffi _X length=2, and Suffix is obtained;

Index=(PrefixNum-3)«3) + Suffix where Index is the index value, PrefixNum is the intermediate variable, and Suffix is the suffix. "" indicates a bitwise left shift operation.

The entropy decoding method according to claim 10, wherein the obtaining the first parameter and the second parameter according to the index value is specifically:

In the determined variable length decoding mode, the preset parameter table is searched according to the index value, and the first parameter and the second parameter corresponding to the index value are obtained.

The entropy decoding method according to claim 1, wherein "decoding according to the type of the current codeword by using a corresponding decoding method" is specifically: when determining that the current codeword is a fixed length codeword Determining, the decoding mode is a fixed-length codeword decoding mode; setting an index value value equal to a fixed-length codeword value, searching a preset fixed-length code table according to the index value, and acquiring a first parameter corresponding to the index value With the second parameter.

The entropy decoding method according to claim 16, wherein the determining that the decoding mode is a fixed length decoding mode is: if the first variable is ≥ 8, determining that the current codeword is The fixed length codeword determines that the decoding mode is a fixed length decoding mode.

18. An apparatus for entropy decoding, the apparatus comprising: an acquiring unit, a codeword type determining unit, and a decoding unit;

The obtaining unit is configured to acquire a first variable according to a binary bit stream;

The codeword type determining unit is configured to determine a type of the current codeword according to the range of the first variable;

The decoding unit is configured to perform decoding according to the type of the current codeword by using a corresponding decoding method.

The entropy decoding apparatus according to claim 18, wherein the acquiring unit comprises:

a bitstream acquisition unit, configured to acquire a binary bitstream;

The first variable acquisition unit is configured to acquire the first variable.

The entropy decoding apparatus according to claim 19, wherein the first variable acquiring unit is specifically:

The number of second non-zero coefficients of the 4X4 block;

The entropy decoding apparatus according to claim 18, wherein the obtaining unit further comprises a prefix obtaining unit, configured to acquire a prefix portion of the codeword in the binary bitstream; the codeword type determining unit, Further for determining, according to the range of the first variable, that the type of the current codeword is a variable length codeword; The decoding unit includes: a decoding mode determining unit, a determining unit, and a special short code decoding unit. The decoding mode determining unit is configured to determine, when the current codeword is a variable length codeword, the decoding mode is Variable length codeword decoding mode;

The special short code decoding unit is configured to: when determining that the current codeword is a special short code, perform decoding according to a preset special short code decoding formula to obtain the first parameter and the second parameter.

22. The entropy decoding apparatus according to claim 21, wherein:

When the determining unit determines that the decoding mode is the variable length codeword decoding mode, determining whether the current codeword is a special short code according to the prefix is specifically:

And assigning the number of “0”s of the prefix part to an intermediate variable, in the variable length codeword decoding mode, if the intermediate variable is smaller than a threshold, determining that the current codeword is a special short code; The code word is a non-special short code.

The entropy decoding apparatus according to claim 22, wherein the codeword type determining unit determines "whether the current codeword is a special short code according to a partial prefix of the codeword", specifically: when -1 ≤ when the first variable <8, it is determined that the type of the current codeword is a variable length codeword;

The decoding mode determining unit includes: a first decoding mode determining unit, a second decoding mode determining unit, a third decoding mode determining unit, and a fourth decoding mode determining unit;

a first decoding mode determining unit, configured to determine, if 0 ≤ the first variable <2, to determine to decode the first decoding mode, where the threshold is 3;

a second decoding mode determining unit, configured to determine that if 2 ≤ the first variable <4, determining to decode the second decoding mode, the threshold is 2;

a third decoding mode determining unit, configured to determine, if 5≤the first variable<8, to determine to decode the third decoding mode, the threshold value is 1; The fourth decoding mode determining unit is configured to determine that if the first variable=−1, determine to decode the fourth decoding mode, where the threshold is 3.

The entropy decoding apparatus according to claim 23, wherein the special short code decoding unit comprises a first special short code decoding unit;

The first special short code decoding unit is configured to: when determining to use the first decoding mode for decoding, TrailingOnes=TotalCoeff=PrefixNum;

The entropy decoding apparatus according to claim 23, wherein the special short code decoding unit further comprises a second special short code decoding unit;

The second special short code decoding unit is configured to: when determining to use the second decoding mode for decoding, reading a binary bit stream according to a preset Suffixlength=l, acquiring Suffix;

TrailingOnes=TotalCoeff=(Prefix« 1 )+Suffix;

The entropy decoding apparatus according to claim 23, wherein the special short code decoding unit further comprises a third special short code decoding unit; and the third special short code decoding unit is configured to determine When decoding is performed using the third decoding mode, reading a binary bit stream according to a preset Suffixlength=3, acquiring Suffix;

TotalCoeff= Suffix; Trailing0nes=3 (Suffix/4)+(Suffix%4) (1 - Suffix/4) or TrailingOnes= 3 Suffix[2:2]+suffix[l:0] x(~ Suffix[2:2 ]);

Among them, TrailingOnes is the first parameter, TotalCoeff is the second parameter, PrefixNum is the intermediate variable, Prefix is the prefix, Suffix is the suffix, and Suffix[2:0] represents the 3rd to the 0th. The special binary number, Suffix[l:0] represents the 2-bit binary number from the 1st to the 0th bit, Suffix[2:2] represents the 1-bit binary number of the 2nd bit, "/" represents the division operator, "% "Indicates the remainder operator, "~" indicates that the bit is inverted.

The entropy decoding apparatus according to claim 23, wherein the special short code decoding unit further comprises a fourth special short code decoding unit; and the fourth special short code decoding unit is configured to determine When decoding using the fourth decoding mode, TrailingOnes = TotalCoeff = 2 PrefixNum[l : l] + (~ PrefixNum[0:0]) x (~ PrefixNum[ 1 : 1]);

The entropy decoding apparatus according to claim 23, wherein the decoding unit further comprises: a non-special short code decoding unit, configured to determine, according to a prefix portion of the codeword, that the current codeword is not a special short In the code length, the preset decoding formula is selected according to the prefix portion of the codeword for decoding in the variable length codeword decoding mode, an index value is obtained, and the first parameter and the second parameter are obtained according to the index value.

The entropy decoding apparatus according to claim 28, wherein the non-special short code decoding unit comprises: a first decoding unit; configured to perform decoding when using the first decoding mode,

((PrefixNum-3)«2) + Suffix 3 < Pr efixNum < 9

Index =

((PrefixNum-9)«3)+Suffix+24 9 < Pr efixNum<l 3

56 + Suffix 13 ≤ Pr efixNum Index is the index value, PrefixNum is the intermediate variable, Suffix is the suffix, Suffixlength is the suffix length, "&&" means the logical AND operator, "?:" means the conditional operator, and "<<" means the bitwise left shift operation.

The entropy decoding apparatus according to claim 28, wherein the non-special short code decoding unit further comprises a second decoding unit; and Suffixlength=(PrefixNum> when decoding is performed using the second decoding mode. =7) ? 3 : 2 Read the binary bit stream according to the Suffixlength, and obtain Suffix;

Index = <j ((PrefixNum-2)«2)+Suffix 2 < Pr efixNum<7

((PrefixNum-7)«3)+Suffix+20 7 < Pr efixNum where Index is the index value, PrefixNum is the intermediate variable, Suffix is the suffix, Suffixlength is the suffix length, "? : " indicates the conditional operator, "<<" Represents a bitwise left shift operation.

The entropy decoding apparatus according to claim 28, wherein the non-special short code decoding unit further comprises a third decoding unit, configured to: when the decoding is performed using the third decoding mode, according to a preset Suffixlength =3 reads the binary bit stream, gets Suffix;

The entropy decoding unit according to claim 28, wherein the non-special short code decoding unit further comprises a fourth decoding unit, configured to use a fourth decoding mode for decoding, according to a preset Suffixlength =2 reads the binary bit stream, gets Suffix;

33. The entropy decoding unit according to claim 28, wherein the non-special short code Determining the "index value in the decoding unit and obtaining the first parameter and the second parameter according to the index value" is specifically:

The entropy decoding apparatus according to claim 21, wherein the decoding mode determining unit further comprises: a fixed length codeword decoding mode determining unit;

a fixed length codeword decoding mode determining unit, configured to determine, if the first variable is ≥8, determine to decode the fixed length codeword decoding mode;

The decoding unit further includes: a fixed length codeword decoding unit, configured to: when determining that the current codeword is a fixed length codeword, determine that the decoding mode is a fixed length codeword decoding mode; And determining a preset fixed length code table according to the index value, and acquiring a first parameter and a second parameter corresponding to the index value.

A recording medium, characterized in that the medium comprises the program of the entropy decoding method of one of claims 1 to 17.